Lens driver

ABSTRACT

A front lens group  1  and a rear lens group  2  having a diameter of about 5 mm held inside a cylindrical body  5  are capable of movement in the forward and backward directions via a front group movable body  3  and a rear group movable body  4 , respectively. An image taking element such as a CCD is arranged at a prescribed position behind the cylindrical body. By setting the distance from each lens group to the CCD and the distance between both lens groups, an image is formed at a prescribed zoom on the CCD. From the 1× base state when the zoom magnification is made α×→β×→γ×, the positional relationship between the front lens group and the rear lens group becomes as shown in FIG.  1 ( b )˜( d ). The two kinds of zoom magnification 1× and β× can be switched by fixing the front lens group and moving only the rear lens group back and forth between positions.

RELATED APPLICATION DATA

This application claims priority of PCT/JP03/13369, filed on Oct. 20,2003, and Japanese Patent Applications No. 2002-306420, filed on Oct.21, 2002 and No. 2003-46010, filed on Feb. 24, 2003, the disclosures ofwhich are incorporated herein in their entirety by reference.

TECHNICAL FIELD

The present invention is related to a lens drive apparatus which makeslenses movable to carry out optical zoom and focusing, and to a lensdrive apparatus which can move lenses to carry out the operations ofoptical zoom, macro and focus, and in particular to an improvement ofdrive operations in a simplified lens structure which can be applied toultraminiature cameras.

PRIOR ART TECHNOLOGY

In recent years, portable telephones equipped with ultraminiaturecameras have become widespread. Such ultraminiature cameras generallyuse a fixed focal point due to size restrictions. The presence orabsence of such ultraminiature cameras holds a big weight in theselection of phone types when a portable telephone is purchased.Further, whether or not a portable telephone is equipped with anultraminiature camera is a big point in the mind of a user, but inactuality not very much concern is given to the performance and functionof the ultraminiature camera.

However, as portable telephones equipped with existing fixed focal pointtype ultraminiature cameras have become widespread, the user who hasbeen using such portable telephones after a normal period of use willnaturally want higher functions in order to be distinguished from otherpeople and the like. One example of a higher function is an optical zoomfunction used in a still camera or a video camera or the like.

In such optical zoom function, a desired zoom is obtained and focusingis carried out in accordance with that zoom normally by appropriatelymoving two or more lens groups in the optical axis direction. Further,as a specific structure for carrying out such process, as shown inJapanese Laid-Open Patent Application No. HEI 7-336938 (Patent Document1), for example, two lenses are respectively moved by independentactuators (stepping motors). Further, as another method, as shown inJapanese Laid-Open Patent Application No. HEI 11-52209(Patent Document2), by using a cam for one actuator or motor, the positionalrelationship of two lenses (lens groups) is controlled, and thisachieves the two operations of zoom and focus.

The movement of the lenses for achieving optical zoom is complex, andinstead of just movement in one direction, a non-linear curve thatincludes a round trip is drawn. In particular, in order to be installedin a portable telephone, the optically effective lens diameter(hereafter “lens diameter”) needs to be less than or equal to φ 7 mm,and should preferably be less than or equal to φ 5 mm, and in the casewhere an ultraminiature lens is used in that way, the position accuracyof the lenses becomes strict, and this requires highly accuratepositioning and a high level of control.

For this reason, in addition to a drive circuit for operating anactuator, there is a need for a circuit which processes data from imagesand sensors for measuring the distance to objects and confirmingpositions and the like, and supplies feedback to the drive circuit. Inother words, this requires highly accurate sensors and data processing,portions requiring control, development, and design man-hours.Furthermore, there is a high cost accompanying an increase in the numberof components, the power consumption becomes larger, and the sizebecomes large scale, whereby it becomes difficult to install in portabletelephones and the like. In particular, as described in Patent Document1, in the case where a drive system is provided for each lens, theproblems described above become more pronounced.

On the other hand, in the case where a cam is used as in the inventiondisclosed in Patent Document 2, this is feasible with one actuator, buta cam and a guide having a plurality of different curvatures arerequired in order to carry out nonlinear movement. For this reason, themovement and the mechanical mechanism are also complex. Furthermore,because the movement of the lenses is very different from the cameramethod, the cam must be developed and designed to such extent.

Further, as shown in Japanese Laid-Open Patent Application No.2002-290523 (Patent Document 3), a drive apparatus equipped with a zoomfunction for installation in a portable telephone achieves zoom by usinga cam for one actuator (motor) to control the positional relationship oftwo longitudinal lenses (group lenses). However, the invention disclosedin the publication described above is a double cylinder cam mechanism inwhich a fixed cylinder for a slot of a linear guide is arranged aroundthe lenses, and a cam cylinder which transmits a driving force isarranged on the outside thereof, and because these are housed in acylindrical housing, there is the problem of the external size becomingbig.

Further, in order to achieve macro operations, a desired macro-focus isobtained by appropriately moving the two longitudinal group lenses inthe optical axis direction, and in this case because the relativepositional relationship of the longitudinal group lenses and the imagetaking element is different from the zoom function, in order to makethese compatible, each group lens needs to be moved independently.However, when a structure is formed in which each group lens isindependently moved by two actuators, the body becomes large, and thismakes it difficult to carry out ultraminiaturization. Further, when zoomand macro operations are obtained using a cam mechanism, the structurethereof becomes complex, and this makes it difficult to carry outultraminiaturization.

In view of the background described above, it is an object of thepresent invention to solve the problems described above without the needfor a complex cam mechanism or highly accurate control or complexmechanisms, and provide a simple miniature lens drive apparatus at lowcost by limiting the zoom magnification. Further, it is another objectto provide a lens drive apparatus having an ultraminiature external sizewhich makes it possible to carry out the operations of optical zoom,macro and focus by one actuator in order to be preferably installed inportable telephones and the like to achieve thinner and smaller scaledevices.

SUMMARY OF THE INVENTION

In order to achieve the objects stated above, the lens drive apparatusaccording to the present invention is a lens drive apparatus for movinglenses in a lens unit having an optical zoom function for use in anultraminiature camera which uses lenses having a lens diameter of 7 mmor less, and is equipped with first and second lens support membersarranged in the front and back, wherein each of said first and secondlens members holds a prescribed number of lenses. Further, in suchproposed structure, said first lens support member is fixed, and saidsecond lens support member is made movable in the forward and backwarddirections and is constructed so as to stop at two prescribed positionsin the forward and backward directions, and this makes it possible toswitch between two kinds of zoom magnification.

Further, as another solution means, in the proposed structure describedabove, said first lens support member is made movable in the forward andbackward directions and is constructed so as to stop at two prescribedpositions in the forward and backward directions, and said second lenssupport member is made movable in the forward and backward directionsand is constructed so as to stop at two prescribed positions in theforward and backward directions, and this makes it possible to switchbetween two kinds of zoom magnification by controlling the stoppingpositions of said first and second lens support members.

In this case, preferably at least one solenoid, relay or permanentmagnet is used as an actuator to move said first lens support member andsaid second lens support member, and this makes it possible to controlthe switching of the two kinds of relative positional relationship bymoving the first and second lens support members in accordance with theoutput of the actuator. When this structure is formed, the switchingcontrol can be achieved by a simpler structure.

Further, as another solution means, in the proposed structure describedabove, said first lens support member is made movable in the forward andbackward directions and is constructed so as to stop at two prescribedpositions in the forward and backward directions, and said second lenssupport member is made movable in the forward and backward directionsand is constructed so as to stop at three prescribed positions in theforward and backward directions, and this makes it possible to switchbetween three kinds of zoom magnification by controlling the stoppingpositions of said first and second lens support members.

In this case, when said second lens support member receives the outputof a stepping motor to move forward and backward, and said first lenssupport member is made movable by a biasing force from said second lenssupport member and is stopped at the two positions of a first positionin the state when said biasing force is not received, and a secondposition when being moved by said biasing force, it is possible toswitch between three kinds of zoom magnification by one actuator and asimple power transmission mechanism. This invention is achieved by thethirteenth embodiment, for example.

Furthermore, in each of the inventions described above, the movement ofat least one of said first lens support member and said second lenssupport member can be carried out based on the output of a steppingmotor.

In this regard, in the embodiments, the first lens support membercorresponds to the member (front group support body 40, front groupmovable body 3, 40′, front lens support body 53, front lens group 61, 71and the like) which supports the front lens group, and the second lenssupport member corresponds to the member (rear group movable body 4, 30,rear lens support body 54, rear lens group 62, 72 and the like) whichsupports the rear lens group, but the present invention is not limitedto this, and depending on the operational characteristics which show therelative relationship between the zoom magnification and the lensposition, the reverse application may also be obtained.

In the present invention, the stopping positions were limited to 2 or 3positions. In this way, positioning can be carried out easily using asimple miniature structure, and by properly setting the stoppingpositions in accordance with the operational characteristics, it ispossible to exhibit different zoom magnifications.

Further, because the number of stopping positions is limited in thisway, even in the case where a plurality of stepping motors are used asactuators, for example, because the positioning of each lens supportmember can be carried out by abutment positioning, it is possible tocarry out highly accurate positioning by simple control. Accordingly,the size of the apparatus does not become larger. Further, these meritsmay be obtained by driving one side with a stepping motor, byattracting/repelling one side with a relay, a solenoid or a permanentmagnet, or by manual operation driving.

Further, using one of any of these as an actuator, by appropriatelytransmitting the output thereof to each of the lens support members, itis possible to obtain different relative positional relationships, andthis makes it possible to change the zoom magnification.

Furthermore, even when the first lens support member is fixed, becauseit is possible to obtain two kinds of zoom magnification byappropriately setting the stopping positions of the second lens supportmember, the present invention can be achieved by an extremely simpleminiature mechanism.

Further, the applied lens diameter is made 7 mm or less for the reasongiven below. Namely, in ultraminiature cameras used in portabletelephones and the like, the surface area of the camera module forms asize less than or equal to 13 mm square even for fixed focusing, andthis level is used as an upper limit. In this regard, in order to fixthe lens, a fixed frame of at least about 1 mm needs to be provided, andthe size of the lens module becomes “lens diameter+2 mm”. Further,because an actuator and a slide mechanism are provided on the outside ofsuch lens module, in order to make the total size 13 mm or less, thelens diameter needs to be made less than or equal to φ 7 mm. Of course,when considering a certain degree of margin and further miniaturizationof the devices into which the camera will be mounted such as portabletelephones and the like, φ 7 mm is the upper limit, and the diameter ispreferably less than or equal to φ 5 mm. Of course, the applicationobject of the lens drive apparatus of the present invention is notlimited to portable telephones.

In order to achieve the other objects described above, the lens driveapparatus according to the present invention is a lens drive apparatusfor moving lenses in a lens unit having an optical zoom function for usein an ultraminiature camera which uses lenses having a lens diameter of7 mm or less, and is equipped with first and second lens support membersarranged in the front and back, wherein each of said first and secondlens members holds a prescribed number of lenses. Further, said firstlens support member is fixed, and said second lens support member ismade movable in the forward and backward directions, is constructed soas to stop at two fixed positions in the forward and backwarddirections, and is driven to move a minute distance at said fixedpositions, whereby it is possible to carry out operations which changeoptical zoom and focus.

In this regard, in the embodiments, the first lens support membercorresponds to the member (frame 3, front group support body 40) whichsupports the front lens group, and the second lens support membercorresponds to the member (frame 4, rear group movable body 30) whichsupports the rear lens group, but the present invention is not limitedto this, and depending on the operational characteristics which show therelative relationship between the zoom magnification and the lensposition, the reverse application may also be obtained.

In the present invention, the stopping positions were limited to 2 fixedpositions, wherein such fixed positions form base positions where minutedistance movement is carried out. In this way, positioning can becarried out easily using a simple miniature structure, and by properlysetting the stopping positions in accordance with the operationalcharacteristics, it is possible to exhibit different zoommagnifications. For this reason, a zoom operation having two values iscarried out even in a structure where only the one second lens supportmember is driven.

Further, because the rear lens is moved minutely at each fixed position,focusing is possible, and this makes it possible to carry out a focusoperation. Further, from the fact that there is movement over a minutedistance, the zoom focal point is moved out of place soon, and focusingtakes place at a focal point existing at a very close position, wherebymacro operations are carried out.

Further, as confirmed by experiment, if the minute movement at saidfixed positions carries out movement by a feed pitch less than or equalto 50 μm for at least a 500 μm section front and back, it is possible toeasily use the macro focal point existing at a very close position.Further, when the feed pitch of said minute movement is made less thanor equal to several μm, the focus operation becomes easy.

Further, a stepping motor is used as a drive source in said drive means,a lead screw is provided on the output shaft of the stepping motor, alead nut is provided at a corresponding position of said second lenssupport member, and a linear operation is carried out by connecting thelead screw and the lead nut. In this case, from the fact that a steppingmotor is used, driving can be carried out over an open loop, thestructure becomes simple without the need for a position detectionsensor or the like, and the drive control becomes easy.

Further, said stepping motor is a flat type in which steps are arrangedon the left and right of the rotor. In this case, because the drivesource becomes flat, the thickness of the lens drive apparatus can begreatly reduced, and this is advantageous in view ofultraminiaturization.

The foregoing and other objects, features and advantages of theinvention will become more readily apparent from the following detaileddescription of a preferred embodiment of the invention that proceedswith reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a rough structural drawing for explaining the concept of eachembodiment of the present invention.

FIG. 2 is an operational characteristics graph showing the positionalrelationship between the zoom magnification and the lens groups.

FIG. 3 is an operational characteristics graph (1 thereof) showing thepositional relationship between the zoom magnification and the lensgroups for explaining the operation principle of the present invention.

FIG. 4 is an operational characteristics graph (2 thereof) showing thepositional relationship between the zoom magnification and the lensgroups for explaining the operation principle of the present invention.

FIG. 5 is an operational characteristics graph (3 thereof) showing thepositional relationship between the zoom magnification and the lensgroups for explaining the operation principle of the present invention.

FIG. 6 is an operational characteristics graph (4 thereof) showing thepositional relationship between the zoom magnification and the lensgroups for explaining the operation principle of the present invention.

FIG. 7 is an operational characteristics graph (5 thereof) showing thepositional relationship between the zoom magnification and the lensgroups for explaining the operation principle of the present invention.

FIG. 8 is an exploded perspective drawing showing a first embodiment ofthe present invention.

FIG. 9 is a perspective drawing showing a first embodiment of thepresent invention.

FIG. 10 is a cross-sectional drawing showing a second embodiment of thepresent invention.

FIG. 11 is a cross-sectional drawing showing a third embodiment of thepresent invention.

FIG. 12 is a cross-sectional drawing showing a fourth embodiment of thepresent invention.

FIG. 13 is a cross-sectional drawing showing a fifth embodiment of thepresent invention.

FIG. 14 is a cross-sectional drawing showing a sixth embodiment of thepresent invention.

FIG. 15 is a drawing showing a modification of a coil.

FIG. 16 is a cross-sectional drawing showing a seventh embodiment of thepresent invention.

FIG. 17 is a cross-sectional drawing showing a seventh embodiment of thepresent invention.

FIG. 18 is a cross-sectional drawing showing an eighth embodiment of thepresent invention.

FIG. 19 is a cross-sectional drawing showing a ninth embodiment of thepresent invention.

FIG. 20 is a cross-sectional drawing showing a tenth embodiment of thepresent invention.

FIG. 21 is a cross-sectional drawing showing an eleventh embodiment ofthe present invention.

FIG. 22 is a drawing showing a twelfth embodiment of the presentinvention.

FIG. 23 is a drawing showing a modification of the twelfth embodiment ofthe present invention.

FIG. 24 is a drawing showing a modification of the twelfth embodiment ofthe present invention.

FIG. 25 is a drawing showing a modification of the twelfth embodiment ofthe present invention.

FIG. 26 is a drawing showing a modification of the twelfth embodiment ofthe present invention.

FIG. 27 is a drawing showing a modification of the twelfth embodiment ofthe present invention.

FIG. 28 is a drawing showing a modification of the twelfth embodiment ofthe present invention.

FIG. 29 is a drawing showing a modification of the twelfth embodiment ofthe present invention.

FIG. 30 is a drawing showing a modification of the twelfth embodiment ofthe present invention.

FIG. 31 is a drawing for describing one example of a drive mechanism ofa movable member in the twelfth embodiment of the present invention.

FIG. 32 is a drawing for describing one example of a drive mechanism ofa movable member in the twelfth embodiment of the present invention.

FIG. 33 is a drawing for describing one example of a drive mechanism ofa movable member in the twelfth embodiment of the present invention.

FIG. 34 is a drawing for describing one example of a drive mechanism ofa movable member in the twelfth embodiment of the present invention.

FIG. 35 is a drawing for describing one example of a drive mechanism ofa movable member in the twelfth embodiment of the present invention.

FIG. 36 is a drawing showing a thirteenth embodiment of the presentinvention.

FIG. 37 is a drawing showing a thirteenth embodiment of the presentinvention.

FIG. 38 is a drawing showing a thirteenth embodiment of the presentinvention.

FIG. 39 is a side view for explaining the concept in a fourteenthembodiment of the present invention.

FIG. 40 is a characteristics graph showing the lens positions for zoommagnification in a fourteenth embodiment of the present invention.

FIG. 41 is a characteristics graph showing the lens positions formingthe macro operation in a fourteenth embodiment of the present invention.

PREFERRED EMBODIMENTS OF THE INVENTION

The present invention will be described in greater detail with referenceto the appended drawings. FIG. 1 is a drawing which explains the conceptof a preferred embodiment of the present invention. As shown in FIG.1(a), in a lens drive apparatus for an ultraminiature camera, a frontlens group 1 and a rear lens group 2 are arranged along an optical axisL. The front lens group 1 and the rear lens group 2 have a diameter of 5mm and are held inside a cylindrical body 5 via a front group movablebody 3 and a rear group movable body 4, respectively. In the example ofthe drawing, because these are movable bodies, the front lens group 1and the rear lens group 2 can both move in the forward and backwarddirections inside the cylindrical body 5. Of course, for conveniencesake in the drawing, an example is shown in which the front lens group 1and the rear lens group 2 are inserted and arranged inside thecylindrical body 5, but in accordance with the driving mechanism of thefront group movable body 3 and the rear group movable body 4, it doesnot need to be a cylindrical body, and it goes without saying that anyappropriate structure may be used.

Further, in order to construct an ultraminiature camera, an image takingelement 6 such as a CCD or the like is arranged at a prescribed rearposition of the cylindrical body 5. In this way, by appropriatelysetting the distance to each of the lens groups 1, 2 and the imagetaking element 6 such as a CCD or the like and the distance between bothlens groups 1, 2, it is possible to form an image at a prescribed zoommagnification. Of course, the output of the image taking element 6 suchas a CCD or the like is inputted into a prescribed image processingapparatus, but because the body structure of the ultraminiature camerahas no relationship with the present invention, a description thereof isomitted. Further, FIG. 1(a) shows the state in which the zoommagnification is 1×.

In the description given below, the relationship of the positions of thetwo lens groups 1, 2 and the zoom magnification (in focus) is like thatshown in FIG. 2. Namely, as shown by the solid line, the movement pathof the front lens group 1 is moved backward so that the zoommagnification is from 1× to α× (e.g., 1.5×), and then when moved forwardslowly, the zoom magnification is increased β× (e.g., 2×)→γ× (e.g.,2.5×). At this time, as shown by the broken line, the movement path ofthe rear lens group 2 is moved forward slowly in order to increase thezoom magnification from 1×.

Further, from the state of the base 1× shown in FIG. 1(a), thepositional relationships of the front lens group 1 and the rear lensgroup 2 at the times when the zoom magnification is α×, β× and γ× areshown in FIGS. 1(b) through (d). Further, the characteristic graph shownin FIG. 2 shows various changes in accordance with the used lens andother mechanisms.

In this regard, in the present invention, it was observed that themovement path of the front lens group 1 for a zoom magnification from 1×to γ× moves forward after first moving backward temporarily. Namely,when viewing the position of the front lens group 1, if A forms theposition at the time when the zoom magnification is the base 1×, thenthe position is the same A when the zoom magnification is β×.Accordingly, if the front lens group 1 is fixed (the front group movablebody 3 is made a simple holding member), and the rear lens group 2 ismade to move freely in a round trip stopping at the two positions (FIGS.1(a), (c)) of the base position (1) and the position (3), it is possibleto achieve a lens drive apparatus in which the zoom magnification hasthe two kinds of magnification 1× and β×. The operation characteristics(zoom magnification and lens position relationship) in this case areshown in FIG. 3.

Further, such structure is achieved by one drive mechanism for the rearlens group 2. Furthermore, because there is a round trip movementbetween the two positions (1), (2), a miniature drive mechanism can beachieved easily by a stepping motor of course, or by a solenoid, arelay, a magnet or the like, and this makes it possible to carry outfurther miniaturization.

Further, when the front lens group 1 and the rear lens group 2 are eachmade independently movable in a round trip between two prescribedpositions, it is possible to achieve a lens drive apparatus for anultraminiature camera which obtains a plurality of zoom magnificationsas described below.

Namely, the front lens group 1 is moved in a round trip to stop at thetwo positions of the base position A and the rear position B, and therear lens group 2 is moved in a round trip to stop at the base position(1) and the front position (2). In this way, by carrying out controllike the operation characteristics shown in FIG. 4, it is possible toachieve a lens drive apparatus which obtains the two zoom magnificationsof the zoom magnification 1× of the base position (FIG. 1(a)) and thezoom magnification α× (FIG. 1(b)). In this example, mechanisms fordriving each of the front lens group 1 and the rear lens group 2 arerequired, but because movement in a round trip is made only between twopositions, each drive mechanism can be simplified, control can also besimplified, and miniaturization is achieved, whereby it becomes possiblefor such structure to be used adequately as a lens drive apparatus foran ultraminiature camera.

In the same way, the front lens group 1 is moved in a round trip to stopat the two positions of the base position A and the front position C,and the rear lens group 2 is moved in a round trip to stop at the baseposition (1) and the front-most position (4). In this way, by carryingout control like the operation characteristics shown in FIG. 5, it ispossible to achieve a lens drive apparatus which obtains the two kindsof zoom magnification of the base position (FIG. 1(a)) and the zoommagnification γ× (FIG. 1(d)). In this example, mechanisms for drivingeach of the front lens group 1 and the rear lens group 2 are required,but because movement in a round trip is made only between two positions,each drive mechanism can be simplified, control can also be simplified,and miniaturization is achieved, whereby it becomes possible for suchstructure to be used adequately as a lens drive apparatus for anultraminiature camera.

Further, the front lens group 1 is moved in a round trip to stop at thetwo positions of the base position A and the rear position B, and therear lens group 2 is moved in a round trip to stop at the base position(1) and the two front positions (2), (3) for a total of three positions.In this way, by carrying out control like the operation characteristicsshown in FIG. 6, it is possible to achieve a lens drive apparatus whichobtains the three kinds of zoom magnification of the zoom magnification1× of the base position (FIG. 1(a)), the zoom magnification α× (FIG.1(b)) and the zoom magnification β× (FIG. 1(c)).

Further, the front lens group 1 is moved in a round trip to stop at thetwo positions of the base position A and the rear position B, and therear lens group 2 is moved in a round trip to stop at the base position(1) and the two front positions (2), (3) for a total of three positions.In this way, by carrying out control like the operation characteristicsshown in FIG. 7, it is possible to achieve a lens drive apparatus whichobtains the three kinds of zoom magnification of the zoom magnification1× of the base position (FIG. 1(a)), the zoom magnification β× (FIG.1(b)) and the zoom magnification γ× (FIG. 1(c)).

Next, a more concrete structure for achieving the above-describedoperating principle will be described. FIG. 8 and FIG. 9 show a firstembodiment. This first embodiment is a type in which the front lensgroup is fixed, and a motor is used as an actuator. FIG. 8 is anexploded perspective drawing, FIG. 9(a) is a perspective drawing showinga base posture (zoom magnification 1×), and FIG. 9(b) is a perspectivedrawing showing a state in which the zoom magnification is β× (2×).

As shown in FIG. 8, a flat rectangular base 10 is formed from a highstep portion 11 which raises ¼ of the area of the front surface thereofincluding one corner by one step, and a low step portion 12 on theremaining area. Further, small diameter holes 13 are formed in three ofthe four corners of the high step portion 11, and a large diameterthrough hole 14 is formed in the middle. The center of the through hole14 forms the optical axis, and although omitted from the drawings, animage taking element such as a CCD or the like is arranged at aprescribed position behind the through hole 14.

Further, a miniature stepping motor 20 is provided on top of the lowstep portion 12. The stepping motor 20 has a case body 21 which iscurved in the shape of a rough arc along the flat shape of the low stepportion 12, and an output shaft 22 which protrudes to the outside isprovided in the middle portion thereof. Although omitted from thedrawings, a rotor is arranged in the middle inside the case body 21, andthe output shaft 22 is inserted in the center of the rotor to form anintegrated body. Further, a stator is arranged in both side portionsextending left and right inside the case body 21. In this regard, thestructure disclosed in Japanese Laid-Open Patent Application No. HEI6-1055828 or Japanese Laid-Open Patent Application No. HEI 6-296358 canbe used as a stepping motor having such structure. Of course, thestepping motor is not limited to such structures, and it goes withoutsaying that it is possible to use various structures. Further, a screwthread is cut in the tip portion of the output shaft 22 to form a leadscrew.

On the other hand, one end of a guide pin 15 is inserted and fixedinside each of the holes 13 provided in the high step portion 11.Further, insertion is carried out so that a rear group movable body 30can move with respect to the guide pins 15. The rear group movable body30 has a flat shape roughly the same as that of the base 10, has guideholes 31 which pass through at positions corresponding to the holes 13of the base 10, and is provided with a through hole 32 at a positioncorresponding to the through hole 14 of the base 10. Further, the guidepins 15 are inserted and arranged inside the guide holes 31, and in thisway, the rear group movable body 30 which is supported by the threeguide pins 15 can move forward and backward along the guide pins 15 in astable posture. Further, a rear lens group (which includes the case ofone lens) omitted from the drawings is mounted inside the through hole32. Accordingly, the rear lens group moves forward and backwardfollowing the forward and backward movement of the rear group movablebody 30. Further, in the state where the rear group movable body 30 ismounted on the guide pins 15, the stepping motor 20 is in an insertedstate between the base 10 and the rear group movable body 30.

Further, a through hole 34 is formed in the portion of the rear groupmovable body 30 corresponding to the output shaft 22 of the steppingmotor 20, and a rectangular concave portion 35 is formed around thethrough hole 34 in the front side of the rear group movable body 30.Further, a lead nut 36 is inserted and fixed inside the concave portion35. The lead nut 36 engages with the lead screw provided on the outputshaft 22 of the stepping motor 20, whereby the lead nut 36 and the reargroup movable body 30 move forward and backward following the positiveand reverse rotations of the output shaft 22.

Further, a front group support body 40 which supports the front lensgroup is mounted to the tip of each guide pin 15. Because the frontgroup support body 40 is fixed to the tip of each guide pin 15, therelative positional relationship with the base 10 and the relativepositional relationship with the CCD do not change. Further, a throughhole 41 is provided in the middle portion of the front group supportbody 40, namely, at a position corresponding to the through holes 14, 32provided in the base 10 and the rear group movable body 30, and thefront lens group is inserted and arranged inside the through hole 41.

Further, a spacer 41 is arranged on each guide pin 15 by insertion. Thethickness of the spacers 43 is set so that the distance between thefront lens group and the rear lens group in the state where the frontgroup support body 40 and the rear group movable body 30 are touchingvia the spacers 43 matches the spacing d1 (see FIG. 3) between the baseposition A of the front lens group and the front position (3) of therear lens group. Furthermore, in the state where the output shaft 22 ofthe stepping motor 20 is rotated in reverse to move the rear groupmovable body 30 the farthest back, the rear lens group is adjusted so asto be positioned at the base position (1). Further, the length of theguide pins 15 are adjusted so that the position of the front lens groupforms the base position A.

As one example of the dimensional shape of the lens drive apparatushaving the structure described above, the base 10 forms an 11 mm square.Further, the inner diameter of the through holes 32, 41, namely, thediameter of the rear lens group and the front lens group is 5 mm.Further, the total height of the apparatus (the distance from the bottomsurface of the base 10 to the front surface of the front group supportbody 40) is approximately 11 mm. In this way, the apparatus can beadequately installed in a portable telephone.

Further, when considering the dimensional shape of existing portabletelephones, the surface area of the camera module forms a size less thanor equal to 13 mm square even for fixed focusing. When this level isused as an upper limit, the lens drive apparatus can be made one sizelarger with a lens diameter up to about 7 mm, and this makes it possibleto keep the total size (flat shape of the base 10) under 13 mm square.Of course, the use of a smaller lens does not interfere with the designof further overall miniaturization.

By forming such structure, when the output shaft 22 of the steppingmotor 20 is rotated in reverse to move the rear group movable body 30backward to a base posture in contact with the front surface of the base10 as shown in FIG. 9(a), the zoom magnification can be set at 1×.

From this state, when the output shaft 22 of the stepping motor 20 isrotated in the positive direction to move the rear group movable body 30forward to form a state in which the front surface of the rear groupmovable body 30 is in contact with the spacers 43 as shown in FIG. 9(b),the zoom magnification can be set at β× (e.g., 2×).

Further, because the stepping motor 20 is used as an actuator, bycontrolling the number of steps, it is possible to control the positionof the rear group movable body 30 with good accuracy, and in the presentembodiment, the rear group movable body 30 may be stopped at the twopositions of the position where contact is made with the base 10, andthe position where contact is made with the spacers 43, and becausethere is contact with another member at either stopping position,positioning can be carried out accurately even by relatively roughcontrol of the number of rotations (number of steps).

FIG. 10 shows a second embodiment of the present invention. In thepresent embodiment, a solenoid is used as an actuator. Namely, as shownin FIG. 10, a front lens group 51 and a rear lens group 52 are mountedinside a bobbin 50 which forms a cylinder so as to be capable ofmovement in the axial direction via a front lens support body 53 and arear lens support body 54, respectively. Further, Teflon (RegisteredTrademark) is added to the inner circumferential surface of the bobbin50, or the bobbin 50 is formed using a resin having a low frictioncoefficient, or at least another cylinder having a mirror-processedinner circumferential surface is inserted or the like to lower thefriction coefficient of the outer circumferential surface of the frontlens support body 53 and the rear lens support body 54 in order to makeit possible to move forward and backward smoothly.

Further, a compression coil spring 55 is inserted and arranged betweenthe front lens support body 53 and the rear lens support body 54 so thatthey are both normally biased in separate directions by the elasticrestoring force of the compression coil spring 55. Further, positioningstoppers 56 which can make contact with the front lens support body 53and the rear lens support body 54 are mounted to both ends of the bobbin50. In this way, the front lens support body 53 and the rear lenssupport body 54 biased by the compression coil spring 55 make contactwith the respective corresponding positioning stoppers 56 and arestopped (see FIG. 10(a)). Further, although omitted from the drawings, aCCD is arranged at a prescribed position behind the bobbin 50 (rear lenssupport body 54 side), and at this time, the dimensions are set so thatthe zoom magnification becomes 1×.

Further, in the present embodiment, the front lens support body 53 andthe rear lens support body 54 are both made from permanent magnets (themagnetic direction is to the left in the drawings), and the positioningstoppers 56 are made from nonmagnetic bodies. Furthermore, a centerpositioning stopper 57 made from a magnetic body is arranged at a middleposition inside the bobbin 50, and a coil 58 is provided around theouter circumference of the bobbin 50. Further, the length of the centerpositioning stopper 57 in the axial direction is made to match thespacing d2 (see FIG. 4) between the rear position B of the front lensgroup and the front position (2) of the rear lens group.

When such structure is formed, in a non-magnetized state, the front lenssupport body 53 and the rear lens support body 54 are biased inrespective separate directions by the elastic restoring force of thecompression coil spring 55, and as shown in FIG. 10(a), this forms abase posture in which contact is made with the positioning stoppers 56provided on the outside. Accordingly, the zoom magnification can be setat 1×.

From this state, as shown in FIG. 10(b), when an electric current ispassed through the coil 58 toward the left in the drawings, thisgenerates an electromagnetic force, and from the magnetic field of thepermanent magnets forming the front lens support body 53 and the rearlens support body 54, the front lens support body 53 and the rear lenssupport body 54 mutually move toward the center and are kept in a stateattracted to the center positioning stopper 57 made from a magneticbody. In this way, the zoom magnification can be set at α× (e.g., 1.5×).

Of course, the electromagnetic force generated by passing an electriccurrent through the coil 58 is set to exhibit a greater force than theelastic restoring force of the compression coil spring 55. Further, oncethe state of FIG. 10(b) is formed, because the front lens support body53 and the rear lens support body 54 are constructed from permanentmagnets, and because they are attracted to the center positioningstopper 57 made from a magnetic body, this state will be maintained evenif the electric current is switched OFF. Further, when an electriccurrent is applied to the coil 58 in the opposite direction, theelectromagnetic force generated by such electric current points in adirection opposite that described above, and this force together withthe elastic restoring force of the compression coil spring 55 pulls thefront lens support body 53 and the rear lens support body 54 apart inseparate directions, and the base posture having a zoom magnification of1× shown in FIG. 10(a) is returned to.

Further, because a solenoid is used as an actuator, it can beconstructed easily on a small scale, and the two positions where thezoom magnification is 1× and α× are set accurately by the positioningstoppers 56 and the center positioning stopper 57.

FIG. 11 shows a third embodiment of the present invention. In thepresent embodiment, the second embodiment described above forms a base,wherein the difference lies in the point that a center positioningstopper 57′ is constructed from a permanent magnet. The magneticdirection (the direction of the arrow in the drawing) of this permanentmagnet points to the left in the drawing, and this matches the magneticdirection of the permanent magnets forming the front lens support body53 and the rear lens support body 54. Further, the other structures arethe same as those of the second embodiment.

In this way, in the non-magnetized state where no electric current isflowing through the coil 58, as shown in FIG. 11(a), the front lenssupport body 53 and the rear lens support body 54 are biased inrespective separate directions by the elastic restoring force of thecompression coil spring 55, and this forms a base posture in whichcontact is made with the positioning stoppers 56 provided on theoutside. Accordingly, the zoom magnification can be set at 1×.

Further, from this state, as shown in FIG. 11(b), when an electriccurrent is passed through the coil 58 toward the left in the drawings,the front lens support body 53 and the rear lens support body 54mutually move toward the center, and when they approach within a certaindegree, the magnetic attractive force of the center positioning stopper57′ made from a permanent magnet also operates to quickly and reliablymaintain an attracted state with the center positioning stopper 57′. Inthis way, the zoom magnification can be set at α× (e.g., 1.5×). Then,even when the electric current to the coil 58 is switched off, the frontlens support body 53 and the rear lens support body 54 are more stronglyfixed by the magnetic attractive force between these bodies and thecenter positioning stopper 57′. Accordingly, in the case of beinginstalled in a portable telephone, for example, it is difficult to holdin a fixed state compared to a digital camera or the like, and it iseasy for the portable telephone itself to shake due to shaking hands orthe like, but because the components are firmly fixed by the permanentmagnets as described above, the zoom magnification can be maintained ina stable state at α×.

Further, in the state where such zoom magnification is α×, when anelectric current is passed in the direction opposite that of FIG. 11(b),the base posture shown in FIG. 11(a) is returned to following the sameprinciple as that of the second embodiment described above. Further,because the other structures and operational effects are the same asthose of the second embodiment described above, the same referencecharacters are used for corresponding members, and a detaileddescription thereof is omitted.

FIG. 12 shows a fourth embodiment of the present invention. In thepresent embodiment, the second embodiment described above forms a base,wherein the difference is the mounting position of compression coilsprings 55′. Namely, a separate compression coil spring 55′ is mountedfor each of the front lens support body 53 and the rear lens supportbody 54. The compression coil springs 55′ are provided outside thebobbin 50, and are set to normally push the front lens support body 53and the rear lens support body 54 toward the center. Namely, in thestate shown in FIG. 12(a), the compression coil springs 55′ are deformedby compression. Further, in an arrangement that is the reverse of thatof the second embodiment, positioning stoppers 56′ provided on both endsof the bobbin 50 are formed by magnetic bodies, and a center positioningstopper 57″ is formed by a nonmagnetic body.

In this way, as shown in FIG. 12(a), the front lens support body 53 andthe rear lens support body 54 made from permanent magnets aremagnetically attracted respectively to the positioning stoppers 56′ madefrom magnetic bodies and are held in a fixed state which forms a baseposture having a zoom magnification of 1×.

Then, from this state, as shown in FIG. 12(b), when an electric currentis passed through the coil 58 toward the left in the drawings, the frontlens support body 53 and the rear lens support body 54 mutually movetoward the center, and when the front lens support body 53 and the rearlens support body 54 move away from the positioning stoppers 56′, theyare positioned and fixed in contact with the center positioning stopper57″ by the magnetic force generated by the electric current and theelastic restoring force of the compression coil springs 55′. In thisway, the zoom magnification can be set in the state α×. In this state,even if the electric current is switched OFF, the front lens supportbody 53 and the rear lens support body 54 are maintained in the stateshown in the drawings by the elastic restoring force of the compressioncoil springs 55.

Further, when an electric current is passed in the opposite directionfrom the state shown in FIG. 12(b), the front lens support body 53 andthe rear lens support body 54 move away from each other, and the baseposture shown in FIG. 12(a) is returned to. After returning, even if theelectric current is switched OFF, because the permanent magnets formingthe front lens support body 53 and the rear lens support body 54 areattracted to the positioning stoppers 56′ made from magnetic bodies,such posture is maintained. Further, because the other structures andoperational effects are the same as those of each embodiment describedabove, the same reference characters are used for corresponding members,and a detailed description thereof is omitted.

Further, in the structure shown in FIG. 12, it is also possible toconstruct the outside positioning stoppers by nonmagnetic bodies, andconstruct the center positioning stopper by a magnetic body or apermanent magnet. In this case, the two compression coil springs 55′ areset to respectively pull the front lens support body 53 and the rearlens support body 54 to the outside. In this way, it is possible toobtain the two kinds of zoom magnification 1× and α× by the same currentpassing principle as that of the embodiments described above.

Further, in the second through the fourth embodiments described above,the front lens support body 53 is fixed to one end of the bobbin 50, andby appropriately passing current in a prescribed direction, it goeswithout saying that it is possible to form a lens drive apparatus whichcan switch between the two kinds of states of the base posture zoommagnification 1× and the zoom magnification β×.

FIG. 13 shows a fifth embodiment of the present invention. In thepresent embodiment, a solenoid is used as an actuator in the same way asin the second through fourth embodiments, and the operationalcharacteristics shown in FIG. 5 are achieved, and this forms a lensdrive apparatus which can obtain the two kinds of zoom magnification 1×and γ×.

The basic apparatus structure is the same as that of the secondembodiment shown in FIG. 10, wherein the positioning stoppers 56arranged on the outside of the bobbin 50 are constructed fromnonmagnetic bodies, and the center positioning stopper 57 is constructedfrom a magnetic body. Further, the front lens support body 53 and therear lens support body 54 are connected to both ends of the compressioncoil spring 55 arranged between both support bodies, and the front lenssupport body 53 and the rear lens support body 54 are biased in separatedirections by the elastic restoring force of the compression coil spring55.

Further, the difference is the position of the front lens group 51(front lens support body 53) at the time of the base posture forming thezoom magnification 1×. Namely, as shown in FIG. 13(a), in the baseposture, the front lens support body 53 is held by magnetic attractionin a state in contact with the center positioning stopper 57. Further,in this state, the rear lens support body 54 is biased backward by theelastic restoring force of the compression coil spring 55 and held in astate pushing against the positioning stopper 56. Further, the magneticdirection (direction of the arrows in the drawings) of the permanentmagnets forming the front lens support body 53 and the rear lens supportbody 54 mutually point toward the center.

In this state, when an electric current is passed toward the left in thedrawings, the front lens support body 53 and the rear lens support body54 mutually move forward (toward the left in the drawings), and as shownin FIG. 13(b), the rear lens support body 54 is magnetically attractedto the center positioning stopper 57, and the front lens support body 53is held in a state pushing against the positioning stopper 56 by theelastic restoring force of the compression coil spring 55. In this way,the front lens support body 53 and the rear lens support body 54 canmutually move forward from the base positions shown in FIG. 13(a), andthe amount of such movements can both be made the same by adjusting thelength and the arrangement position of the center positioning stopper57, or they can be made different. Accordingly, as shown in FIG. 5, bysetting various dimensions, it is possible to form a state in which thezoom magnification is γ× when the front lens support body 53 (front lensgroup 51) reaches the front position C and the rear lens support body 54(rear lens group 52) reaches the front-most position (4).

Then, even if the electric current is switched OFF, the zoommagnification γ× state is maintained. Further, when an electric currentis passed in the opposite direction, the base posture having the zoommagnification 1× shown in FIG. 13(a) is returned to. Accordingly, in thepresent embodiment, it is possible to construct a lens drive apparatuswhich obtains the two kinds of zoom magnification 1× and γ× from theoperational characteristics shown in FIG. 5. Further, because the otherstructures and operational effects are the same as those of each of theembodiments described above, the same reference characters are used forcorresponding members, and a detailed description thereof is omitted.

FIG. 14 shows a sixth embodiment of the present invention. In thepresent embodiment, the fifth embodiment described above forms a base,and two compression coil springs 55′ are provided in the same way as inthe fourth embodiment to respectively bias the front lens support body53 and the rear lens support body 54 in respective prescribeddirections.

Namely, the center positioning stopper 57″ is constructed from anonmagnetic body, and both positioning stoppers 56′ are constructed frommagnetic bodies. Further, the magnetic direction (direction of thearrows in the drawings) of the permanent magnets forming the front lenssupport body 53 and the rear lens support body 54 point forward in thesame direction (toward the left in the drawings). Further, thecompression coil springs 55′ bias the corresponding support bodies 53,54 toward the center positioning stopper 57″. However, the elasticrestoring force thereof does not negate the state in which the lenssupport bodies 53, 54 are magnetically attracted to the positioningstoppers 56′ and pull them apart, but is instead a force greater thanthe magnetic attractive force created between the lens support bodies53, 54 and the positioning stoppers 56′ once the lens support bodies 53,54 are separated from the positioning stoppers 56′ and push against thecenter positioning stopper 57″.

When such structure is formed, as shown in FIG. 14(a), in the baseposture, the front lens support body 53 is pushing against the centerpositioning stopper 57″ by the elastic restoring force of thecompression coil spring 55′, and the rear lens support body 54 is heldin a magnetically attracted state to the positioning stopper 56′. Inthis state, the zoom magnification is set at 1×.

From this state, when an electric current is passed through the coil 58,as shown in FIG. 14(b), the front lens support body 53 and the rear lenssupport body 54 move forward (toward the left in the drawings) by themagnetic force. Then, while the compression coil spring 55 is deformedby compression, the front lens support body 53 moves forward and isfixed to the positioning stopper 56′ by magnetic attraction. In the sameway, the rear lens support body 54 is pushed against the centerpositioning stopper 57″ and fixed in place by the elastic restoringforce of the compression coil spring 55. In this way, by setting thedimensional shape and arrangement position of the center positioningstopper 57″ in the same way as in the fifth embodiment, it is possibleto set the zoom magnification at γ×.

Of course, even in this embodiment, the state shown in FIG. 14(a) can bereturned to by passing an electric current in a direction opposite thatof FIG. 14(b). Further, an electric current is passed only at the timethe zoom magnification is changed, and after changing, such state ismaintained even if the electric current is switched OFF. Further,because the other structures and operational effects are the same asthose of each of the embodiments described above, the same referencecharacters are used for corresponding members, and a detaileddescription thereof is omitted.

In the second through the sixth embodiments described above, in eachcase the coil 58 wound around the bobbin 50 used a uniform winding inthe axial direction, but the present invention is not limited to this,and by changing the number of windings in accordance with location, itis possible to give a gradient to the magnetic field. Namely, by makingthe magnetic field the strongest at the stopping positions, it ispossible to make it easy to obtain a driving force required for zooming.

Further, in order to give a gradient to the magnetic field, the coil maybe provided with coils 58 a, 58 b having a different number of windings,and these may be arranged in the axial direction as shown in FIG. 15(a),or the coil may be made to have a changing number of windings in theaxial direction as shown in FIG. 15(b), for example. Further, no matterwhich positions have a strong magnetic field, these are set in view ofthe lens support body stopping positions or the like, but they are notnecessarily limited to the end portions.

FIG. 16 and FIG. 17 show a seventh embodiment of the present invention.In the present embodiment, the difference with the embodiments describedabove is a structure which uses an electromagnet as an actuator.Further, this is a type (operational characteristics shown in FIG. 5)which obtains the two kinds of zoom magnification 1× and α×.

Namely, a cylinder 63 in which a front lens group 61 and a rear lensgroup 62 are mounted so as to be capable of movement in the axialdirection, and an electromagnet 65 are arranged close together inparallel inside a rectangular frame 60. Further, the innercircumferential surface of the cylinder 63 is also formed to have a lowfriction coefficient so that the front lens group 61 and the rear lensgroup 62 can move forward and backward smoothly.

Further, both ends of the electromagnet 65 are provided with a core 65a, and the tips of the cores 65 a overlap with the cylinder 63. The tipportions of the cores 65 a form portions which generate anelectromagnetic force by the electromagnet 65. Further, an image takingelement 69 such as a CCD or the like is arranged at the rear end portionof the frame 60, and light which is incident via the front lens group 61and the rear lens group 62 forms an image on the image taking element69.

Further, the front lens group 61 and the rear lens group 62 areconstructed to include a prescribed number of lenses and support bodieswhich support these. Further, a structure is formed in which the frontlens group 61 and the rear lens group 62 are normally biased toward thecenter by compression coil springs 64 arranged between these groups andspring stopping portions 63 a provided at both ends of the cylinder 63.Further, two positioning stoppers 66 and one center positioning stopper67 are arranged at prescribed positions on a line connecting the tips ofthe cores 65 a provided at both ends of the electromagnet 65, andpermanent magnets 68 are provided buried inside the outer circumferenceof the front lens group 61 and the rear lens group 62. Morespecifically, as shown in FIG. 17(a), the positioning stoppers 66 areformed from magnetic bodies and are provided respectively at positionsnear both cores 65 a so that the front lens group 61 and the rear lensgroup 62 are stopped by making respective contact therewith. This stateforms a base posture in which each of the lens groups 61, 62 ispositioned at a base position to set the zoom magnification at 1×.

Further, the center positioning stopper 67 is formed from a permanentmagnet, and the magnetic direction (direction of the arrow in thedrawings) is the same direction (front direction) as that of thepermanent magnets 68 buried respectively in the front lens group 61 andthe rear lens group 62. Further, as shown in FIG. 17(b), the length andthe arrangement position of the center positioning stopper 67 is set sothat the front lens group 61 and the rear lens group 62 are positionedat the rear position B and the front position (2), respectively, at thetime when both are close together pushing against the center positioningstopper 67.

When such structure is formed, in the base posture, as shown in FIG.17(a), the compression coil springs 64 are deformed by compression, andthe front lens group 61 and the rear lens group 62 are fixed by themagnetic attractive force from the permanent magnets 68 in a statemaking contact respectively with the positioning stoppers 66 provided onthe outside. Accordingly, the zoom magnification can be set at 1×.

Then, from this state, when an electric current is passed through theelectromagnet 65, a magnetic field like that shown in FIG. 17(b) isgenerated, and this generated magnetic field magnetically repels thepermanent magnets 68 provided in the front lens group 61 and the rearlens group 62, and the front lens group 61 and the rear lens group 62are separated from the positioning stoppers 66 and moved toward thecenter by the elastic restoring force of the compression coil springs64. Further, the front lens group 61 and the rear lens group 62 arestopped in a state where they are pushing against the center positioningstopper 67. In this way, the zoom magnification can be set at α×.

Further, even if the electric current to the electromagnet 65 isswitched OFF, the state shown in FIG. 17(b) is maintained by themagnetic attractive force generated between the permanent magnets 68provided in the front lens group 61 and the rear lens group 62 and thecenter positioning stopper 67 formed from a permanent magnet.

Further, in the state shown in FIG. 17(b), when an electric current ispassed through the electromagnet 65 in the opposite direction, thepermanent magnets 68 are mutually moved to the outside by the magneticattractive force of the electromagnet 65, and the zoom magnificationstate 1× shown in FIG. 17(a) is returned to. Then, this state ismaintained even if the electric current is switched OFF. Further,because the other structures and operational effects are the same asthose of each of the embodiments described above, a detailed descriptionthereof is omitted.

FIG. 18 shows an eighth embodiment of the present invention. In thepresent embodiment, the seventh embodiment described above forms a base,wherein the difference lies in the point that a center positioningstopper 67′ is constructed from a magnetic body, and the otherstructures are the same. When such structure is formed, in the baseposture shown in FIG. 18(a), the zoom magnification can be set at 1×,and from this state, as shown in FIG. 18(b), when an electric current ispassed through the electromagnet 65, the permanent magnets 68 providedin the front lens group 61 and the rear lens group 62 are repelled bythe magnetic field generated by the electromagnet 65, and this moves thefront lens group 61 and the rear lens group 62 toward the center.Accordingly, the zoom magnification can be set at α×. Of course, fromthe state of FIG. 18(b), it is possible to return to the state of FIG.18(a) by passing an electric current through the electromagnet 65 in theopposite direction. Further, because the other states and operationaleffects are the same as those of the seventh embodiment described above,the same reference characters are used for corresponding members, and adetailed description thereof is omitted.

FIG. 19 shows a ninth embodiment of the present invention. In thepresent embodiment, the seventh and eighth embodiments described aboveform a base. Further, the point of difference is the provision of onecompression coil spring 64′ between the front lens group 61 and the rearlens group 62, wherein the front lens group 61 and the rear lens group62 are biased away from each other by the elastic restoring force of thecompression coil spring 64′. Further, the positioning stoppers 66′provided at both ends are formed from nonmagnetic bodies, and the centerpositioning stopper 67′ is formed from a magnetic body. Furthermore, thecore 65 a provided in the electromagnet 65 is provided in a centerportion of the electromagnet 65 in the axial direction. Morespecifically, it is preferably positioned near the center positioningstopper 67′. Further, the magnetic direction (direction of the arrows inthe drawings) of the permanent magnets 68 provided in the front lensgroup 61 and the rear lens group 62 point in mutually oppositedirections. Of course, even though omitted from the drawings, an imagetaking element is arranged at a prescribed position behind the frame 60.

When such structure is formed, in the base posture in which no electriccurrent is flowing through the electromagnet 65, as shown in FIG. 19(a),the front lens group 61 and the rear lens group 62 are separated by theelastic restoring force of the compression coil spring 64′ and are fixedin position by being pushed against the positioning stoppers 66′provided at both ends of the cylinder 63. In this way, the zoommagnification can be set at 1×.

From this state, as shown in FIG. 19(b), when a magnetic field like thatshown in the drawings is generated by passing an electric currentthrough the electromagnet 65, the permanent magnets 68 are magneticallyattracted and move to the center. In this way, the front lens group 61and the rear lens group 62 are fixed in position in a state makingcontact with the center positioning stopper 67′, and even if theelectric current to the electromagnet 65 is switched OFF in this state,the compression deformed state of the compression coil spring 64′ ismaintained by the magnetic attractive force between the permanentmagnets 68 and the center positioning stopper 67′. Accordingly, the zoommagnification can be set at α×.

Of course, from this state it is possible to return to the state shownin FIG. 19(a) by applying an electric current to the electromagnet 65 ina direction opposite that shown in FIG. 19(b). Further, because theother structures and operational effects are the same as those of theseventh and eighth embodiments described above, the same referencecharacters are used for corresponding members, and a detaileddescription thereof is omitted.

FIG. 20 shows a tenth embodiment of the present invention. In thepresent embodiment, an electromagnet is used as an actuator in the sameway as in the seventh through ninth embodiments shown in FIG. 18,wherein the operational characteristics shown in FIG. 5 are achieved,and this forms a lens drive apparatus which can obtain the two kinds ofzoom magnification 1× and γ×.

The basic structure is the same as that of the eighth embodiment,wherein the positioning stoppers 66 arranged at both ends of thecylinder 63 are constructed from magnetic bodies, and the centerpositioning stopper 67′ is also constructed from a magnetic body.Further, the front lens group 61 and the rear lens group 62 areconnected to both ends of the compression coil spring 64′ arrangedbetween both lens groups, and the front lens group 61 and the rear lensgroup 62 are biased in separate directions by the elastic restoringforce of the compression coil spring 64′.

Further, the difference is the position of the front lens group 61 atthe time of the base posture forming the zoom magnification 1×. Namely,as shown in FIG. 20(a), in the base posture, the front lens group 61 isheld by magnetic attraction in a state in contact with the centerpositioning stopper 67′. Further, in this state, the rear lens group 62is biased backward by the elastic restoring force of the compressioncoil spring 64′ and held in a state pushing against the positioningstopper 66. Further, the magnetic direction (direction of the arrows inthe drawings) of the permanent magnets 68 provided in the front lensgroup 61 and the rear lens group 62 mutually point toward the outside.

In this state, when an electric current is passed through theelectromagnet 65, a magnetic field due to the electromagnet 65 isgenerated as shown in FIG. 20(b), whereby the permanent magnets 68 areattracted/repelled, and the front lens group 61 and the rear lens group62 mutually move forward (toward the left in the drawings), the rearlens group 62 is magnetically attracted to the center positioningstopper 67′, and the front lens group 61 is held in a state pushingagainst the positioning stopper 66 by the elastic restoring force of thecompression coil spring 64′. In this way, the front lens group 61 andthe rear lens group 62 can mutually move forward from the base postureshown in FIG. 20(a), and the amount of such movements can both be madethe same by adjusting the length and the arrangement position of thecenter positioning stopper 67′, or they can be made different.Accordingly, as shown in FIG. 5, by setting various dimensions, it ispossible to set the zoom magnification at γ× when the front lens group61 reaches the front position C and the rear lens group 62 reaches thefront-most position (4).

Then, even if the electric current is switched OFF, the zoommagnification γ× state is maintained. Further, when an electric currentis passed in the opposite direction, the base posture having the zoommagnification 1× shown in FIG. 20(a) is returned to. Accordingly, in thepresent embodiment, it is possible to construct a lens drive apparatuswhich obtains the two kinds of zoom magnification 1× and γ× from theoperational characteristics shown in FIG. 5. Further, because the otherstructures and operational effects are the same as those of each of theembodiments described above, the same reference characters are used forcorresponding members, and a detailed description thereof is omitted.

FIG. 21 shows an eleventh embodiment of the present invention. Thepresent embodiment is the type which obtains the two kinds of zoommagnification 1× and γ× in the same way as in the tenth embodimentdescribed above. As shown in FIG. 21, in the present embodiment, theelectromagnet 65 is different compared to that of the tenth embodiment.Namely, a core 65 a is provided in a center position of theelectromagnet 65. In actuality, this is achieved by interposing the core65 a between two electromagnets 65. The structure of the electromagnets65 is the same as that in the ninth embodiment shown in FIG. 19.Further, the magnetic direction (direction of the arrows in thedrawings) of the permanent magnets 68 provided respectively in the frontlens group 61 and the rear lens group 62 both point backward in the samedirection (toward the right in the drawings). Further, the positioningstoppers 66′ provided at both ends of the cylinder 63 are made fromnonmagnetic bodies.

When such structure is formed, from the state (zoom magnification 1×) ofthe base posture shown in FIG. 21, by passing an electric currentthrough the electromagnets 65 in a prescribed direction, as shown inFIG. 21(b), the front lens group 61 and the rear lens group 62 both moveforward, and this makes it possible to set the zoom magnification at γ×.Further, by passing an electric current in a direction opposite that ofFIG. 21(b) from such state, it is possible to return to the state shownin FIG. 21(a). Further, because the other structures and operationaleffects are the same as those of each of the embodiments describedabove, the same reference characters are used for corresponding members,and a detailed description thereof is omitted.

From FIG. 22 onward, a permanent magnet is used as an actuator. FIG. 22shows the essential portion of a twelfth embodiment of the presentinvention. Namely, in the present embodiment, slide guides 73 aremounted at prescribed positions of the outer circumference of a frontlens group 71 and a rear lens group 72, whereby the front lens group 71and the rear lens group 72 can freely move in the axial direction alonga slide shaft 74 via the slide guides 73. Of course, the front lensgroup 71 and the rear lens group 72 use a structure in which the lensesare mounted inside support bodies, wherein the optical axes of thelenses are aligned. Further, these elements are arranged so that animage is formed on an image taking element such as a CCD or the likeomitted from the drawings arranged behind the rear lens group 72.

Further, positioning stoppers 75 are mounted at prescribed positions ofboth ends of the slide shaft 74, and a center positioning stopper 76 isprovided at a middle point of the slide shaft 74. In this way, the frontlens group 71 and the rear lens group 72 can move between the centerpositioning stopper 76 and the positioning stoppers 75. Further, thedistance between the positioning stoppers 75 and the length and thearrangement position of the center positioning stopper 76 are set so asto obtain the operational characteristics shown in FIG. 4.

Namely, as shown in FIG. 22(a), in the state where the slide guides 73of the front lens group 71 and the rear lens group 72 are both makingcontact with the positioning stoppers 75, the front lens group 71 andthe rear lens group 72 are set so as to be positioned at the basepositions A and (1), respectively. In this way, the zoom magnificationcan be set at 1×.

Further, as shown in FIG. 22(b), in the state where the slide guides 73of the front lens group 71 and the rear lens group 72 are both makingcontact with the center positioning stopper 76, the front lens group 71and the rear lens group 72 are set so as to be positioned at the rearposition B and the front position (2), respectively. In this way, thezoom magnification can be set at α×.

Further, as an example of the drive mechanism for switching the zoommagnification between 1× and α×, permanent magnets 77 are provided inthe front lens group 71 and the rear lens group 72, and a movable member78 formed from a magnetic body is inserted so as to freely appear anddisappear (be inserted and removed) between the permanent magnets 77.Namely, because the facing surfaces have the same pole, the permanentmagnets 77 repel each other. In this way, as shown in FIG. 22(a), whenthe movable member 78 formed from a magnetic body is not insertedbetween the permanent magnets 77, the permanent magnets 77 move in adirection away from each other due to magnetic repulsion, and the slideguides 73 are fixed in position in a state making contact with thepositioning stoppers 75.

In this state, as shown in FIG. 22(b), when the movable member 78 formedfrom a magnetic body is inserted between the permanent magnets 77, bothpermanent magnets 77 are magnetically attracted to the movable member78, and this makes both permanent magnets 77 approach the movable member78 formed from a magnetic body. In this way, the slide guides 73 arefixed in a state making contact with the center positioning stopper 76.Of course, when the movable member 78 formed from a magnetic body isremoved from this state, the state shown in FIG. 22(a) is returned to.

Further, in the present embodiment, it is possible to make variouschanges to the embodiment. Namely, as shown in FIG. 23, for example,permanent magnets 78 a can be attached to both sides of the movablemember 78 formed from a magnetic body, and this forms a magneticattraction between the attached permanent magnets 78 a and the permanentmagnets 77 provided in the front lens group 71 and the rear lens group72.

In this way, in the case where the movable member 78 formed from amagnetic body is removed, the permanent magnets 77 magnetically repeleach other in the same way as in the twelfth embodiment, and the baseposture shown in FIG. 23(a) is maintained. Then, from this state, whenthe movable member 78 formed from a magnetic body and having theattached permanent magnets 78 a is inserted between the permanentmagnets 77 as shown in FIG. 23(b), a magnetic attraction is createdbetween mutually facing permanent magnets 77, 78 a, whereby theyapproach more smoothly, and this state (the state where the zoommagnification is α×) can be maintained more securely. Further, becausethe other structures and operational effects are the same as those ofthe twelfth embodiment described above, the same reference charactersare used for corresponding members, and a detailed description thereofis omitted.

As an example of another embodiment, as shown in FIG. 24, with thetwelfth embodiment forming a base, a structure can be formed in whichthe permanent magnets 77 mounted in the front lens group 71 and the rearlens group 72 are made thin (roughly half) and arranged at facing sides,and magnetic bodies 77 a are arranged on the opposite sides (outside).When this is done, it is possible to reduce the amount of use ofexpensive permanent magnets, and this makes it possible to expect a costreduction result. Further, because the other structures and operationaleffects are the same as those of the twelfth embodiment described above,the same reference characters are used for corresponding members, and adetailed description thereof is omitted.

Further, as shown in FIG. 25, it is possible to use the force ofcompression coil springs 79. Namely, with the twelfth embodiment forminga base, one end of each of the compression coil springs 79 is fastenedto the outside of the permanent magnets 77 provided in the front lensgroup 71 and the rear lens group 72. Of course, the other ends of thecompression coil springs 79 have positions which are restricted byspring restrictors (see characters 63 a in FIG. 17 or the like) or thelike.

In this way, as shown in FIG. 25(a), when the movable member 78 formedfrom a magnetic body is removed from between the permanent magnets 77,the permanent magnets 77 repel each other and are held apart while thecompression coil springs 79 are deformed by compression, and the zoommagnification is set at 1×. Further, as shown in FIG. 25(b), when themovable member 78 is inserted between the permanent magnets 77, inaddition to the magnetic attraction between the movable member 78 andthe permanent magnets 77, the elastic restoring force of the compressioncoil springs 79 make it possible to quickly set the zoom magnificationat α× as shown in the drawings. Further, because the other structuresand operational effects are the same as those of the twelfth embodimentdescribed above, the same reference characters are used forcorresponding members, and a detailed description thereof is omitted.

Further, by using the compression coil springs 79 as described above, asshown in FIG. 26, for example, magnetic bodies 77′ can be mounted in thefront lens group 71 and the rear lens group 72, and a movable member 78′formed from a permanent magnet can be inserted and removed between themagnetic bodies 77′. In this way, as shown in FIG. 26(a), when themovable member 78′ formed from a permanent magnet is removed frombetween the magnetic bodies 77′, the magnetic bodies 77′ together withthe front lens group 71 and the rear lens group 72 are held apart by theelastic restoring force of the compression coil springs 79, the zoommagnification can be set at 1×, and this makes it possible to positionthe slide guides 73 in firm contact with the positioning stoppers 75.

In this state, as shown in FIG. 26(b), when the movable member 78′formed from a permanent magnet is inserted between the magnetic bodies77′, a magnetic attractive force is generated, and this makes itpossible to attract and fix both magnetic bodies 77′. Further, becausethe other structures and operational effects are the same as those ofthe twelfth embodiment described above, the same reference charactersare used for corresponding members, and a detailed description thereofis omitted.

Further, as shown in FIG. 27, it is possible to use permanent magnets 77in place of the magnetic bodies 77′ in the embodiment shown in FIG. 26.In this case, as shown in FIG. 27(a), in the state where the movablepermanent magnet 78′ is not present, the elastic restoring force of thecompression coil springs 79 is greater than the magnetic attractiveforce between the permanent magnets 77 mounted in the front lens group71 and the rear lens group 72, and the zoom magnification is set at 1×as shown in the drawings. Then, when the movable member 78′ formed froma permanent magnet is inserted between the permanent magnets 77, a largemagnetic attractive force is generated between the movable member 78′and the permanent magnets 77, and as shown in FIG. 27(b), the slideguides 73 are stopped by being pushed against the center positioningstopper 76. In this way, the zoom magnification can be set at α×.Further, because the other structures and operational effects are thesame as those of the twelfth embodiment described above, the samereference characters are used for corresponding members, and a detaileddescription thereof is omitted.

FIG. 28 shows another embodiment. In this embodiment, a centerpositioning stopper 76′ is mounted to both sides of the movable member78 formed from a magnetic body. In this way, in the state where themovable member 78 is removed as shown in FIG. 28(a), the permanentmagnets 77 repel each other, and the slide guides 73 are fixed inposition making contact with the positioning stoppers 75 at both ends.Further, in the case where the movable member 78 is inserted between thepermanent magnets 77, a magnetic attraction is created between themagnetic body 78 and the permanent magnets 77, and as shown in FIG.28(b), the permanent magnets 77 make contact with the center positioningstoppers 76′, and this position is maintained. Of course, from thisstate, when the movable member 78 formed from a magnetic body is movedto the outside, the permanent magnets 77 repel each other, and the stateshown in FIG. 28(a) is returned to. Further, because the otherstructures and operational effects are the same as those of the twelfthembodiment described above, the same reference characters are used forcorresponding members, and a detailed description thereof is omitted.

FIG. 29 shows another embodiment. In this embodiment, the twelfthembodiment forms a base, and auxiliary magnets 80 are provided near thestopping positions (see FIG. 29(a)) at the time when the movable member78 formed from a magnetic body is moved to the outside. Moreover, thespacing of the auxiliary magnets 80 is shorter than the spacing of thepermanent magnets 77 at the time when the front lens group 71 and therear lens group 72 repel each other as shown in FIG. 29(a), and as shownin FIG. 29(b), is longer than the spacing of the permanent magnets 77 atthe time when the front lens group 71 and the rear lens group 72 aremagnetically attracted. In this way, as is clear from FIGS. 29(a), (b),because the spacing of the pair of permanent magnets 77 is shorter thanthe spacing of the auxiliary magnets 80 when the movable member 78formed from a magnetic body is inserted, such state is stabilized, andeven in the case where the movable member 78 is moved and removed fromsuch state, because the permanent magnets 77 or the auxiliary magnets 80are near, it is possible to move the movable member 78 smoothly by asmall force when it is removed from the present state. Further, becausethe other structures and operational effects are the same as those ofthe twelfth embodiment described above, the same reference charactersare used for corresponding members, and a detailed description thereofis omitted.

Further, in the technological concept shown in FIG. 29 described above,in the case where the movable member 78′ is a permanent magnet as shownin FIG. 30, for example, it is possible to achieve the same function byproviding auxiliary magnetic bodies 80′ in place of the auxiliarymagnets 80.

In the twelfth embodiment and the various embodiments that followeddescribed above, the specific drive mechanism for moving the movablemembers 78, 78′ can use the various structures shown in FIG. 31 onward.First, in both FIG. 31 and FIG. 32, movement is carried out by manualcontrol. Namely, in FIG. 31, an operation lever 82 is provided on themovable member 78 formed from a magnetic body, and by holding and movingthe operation lever 82 back and forth on a straight line, the user canswitch between the two states of the state of the base posture (zoommagnification 1×) when the movable member 78 is removed from between thepermanent magnets 77 as shown in FIG. 31(a), and the state where thezoom magnification is α× when the movable member 78 is inserted betweenthe permanent magnets 77 as shown in FIG. 31(b).

Further, in the embodiment described above, the movable member 78 andthe operation lever 82 are made to carry out linear motion, but as shownin FIG. 32, an operation lever 83 having one end attached to the movablemember 78 formed from a magnetic body is connected to a rotation shaft83 a, and an operation portion 84 is provided on the other end of theoperation lever 82. In this way, by moving the operation portion 84roughly up and down (in actuality, movement is along an arc-shapedpath), the operation lever 83 rotates within a prescribed angular rangein the positive and reverse directions around the rotation shaft 83 a.Accordingly, it is possible to switch between the two states of thestate of the base posture (zoom magnification 1×) when the movablemember 78 is removed from between the permanent magnets 77 as shown inFIG. 32(a), and the state where the zoom magnification is α× when themovable member 78 is inserted between the permanent magnets 77 as shownin FIG. 32(b).

Further, as shown in FIG. 33, with the structure shown in FIG. 32forming a base, it is possible for the rotation shaft 83 a to be madethe output shaft of a stepping motor 85. When such structure is used, byrotating the stepping motor 85 in the positive and reverse directions,it is possible to automatically insert and remove the movable member 78between the permanent magnets 77 to switch the zoom magnification (seeFIG. 33(a), (b)).

Furthermore, it is possible to use a linear actuator 86 as the actuatorwhen the movable member 78 is moved automatically. Namely, as shown inFIG. 34, the movable member 78 is provided in the tip of a rod 86 awhich moves back and forth in a straight line forming the linearactuator 86, and adjustments are carried out so that the base posture(zoom magnification 1×) is obtained (see FIG. 34(a)) when the movablemember 78 is removed from between the permanent magnets 77 in the casewhere the rod 86 a is pulled back, and the zoom magnification becomes α×(see FIG. 34(b)) when the movable member 78 is inserted between thepermanent magnets 77 in the case where the rod 86 a is protruding themost. In this way, by driving the linear actuator 86 a by operating aswitch omitted from the drawings, it is possible to switch between twozoom magnifications.

Further, as shown in FIG. 35, even when a curved rod 87 a is used as anactuator 87 using back and forth movement along an arc shape, it ispossible to switch between two kinds of zoom magnification based on aswitch operation the same as that described above.

Further, the specific examples of each drive mechanism described abovewere shown as being applied to the twelfth embodiment, but it is ofcourse possible to apply the same structures to the other embodiments.

FIGS. 36˜38 show a thirteenth embodiment of the present invention. Thepresent embodiment achieves the operational characteristics shown inFIG. 7, and uses a stepping motor as an actuator for moving the lensgroups.

The basic structure is the same as that of the first embodiment, whereinthe difference is that the front lens group is also made movable.Namely, as shown in FIGS. 36˜38, a flat rectangular base 10 is formedfrom a high step portion 11 which raises ¼ of the area of the frontsurface thereof including one corner by one step, and a low step portion12 on the remaining area. Further, small diameter holes 13 are formed inthree of the four corners of the high step portion 11, and a largediameter through hole 14 is formed in the middle. The center of thethrough hole 14 forms the optical axis, and although omitted from thedrawings, an image taking element or the like such as a CCD or the likeis arranged at a prescribed position behind the through hole 14.

Further, a miniature stepping motor 20 is provided on top of the lowstep portion 12. The stepping motor 20 has a case body 21 which iscurved in the shape of a rough arc along the flat shape of the low stepportion 12, and an output shaft 22 which protrudes to the outside isprovided in the middle portion thereof. Although omitted from thedrawings, a rotor is arranged in the middle inside the case body 21, andthe output shaft 22 is inserted in the center of the rotor to form anintegrated body. Further, a stator is arranged in both side portionsextending left and right inside the case body 21. In this regard, thestructure disclosed in Japanese Laid-Open Patent Application No. HEI6-1055828 or Japanese Laid-Open Patent Application No. HEI 6-296358 canbe used as a stepping motor having such structure. Of course, thestepping motor is not limited to such structures, and it goes withoutsaying that it is possible to use various structures. Further, a screwthread is cut in the tip portion of the output shaft 22 to form a leadscrew.

On the other hand, one end of a main guide pin 15 a, sub guide pin 15 bis inserted and fixed inside each of the holes 13 provided in the highstep portion 11. Further, insertion is carried out so that a rear groupmovable body 30 can move with respect to both guide pins 15 a, 15 b. Therear group movable body 30 has a flat shape roughly the same as that ofthe base 10, has guide holes 31 which pass through at positionscorresponding to the holes 13 of the base 10, and is provided with athrough hole 32 at a position corresponding to the through hole 14 ofthe base 10. Further, both guide pins 15 a, 15 b are inserted andarranged inside the through hole 32, and in this way, the rear groupmovable body 30 which is supported by both the main guide pins 15 a andthe sub guide pins 15 b can move forward and backward along each of theguide pins 15 a, 15 b in a stable posture. Further, a rear lens group(which includes the case of one lens) omitted from the drawings ismounted inside the through hole 32. Accordingly, the rear lens groupmoves forward and backward following the forward and backward movementof the rear group movable body 30. Further, in the state where the reargroup movable body 30 is mounted on each of the guide pins 15 a, 15 b,the stepping motor 20 is in an inserted state between the base 10 andthe rear group movable body 30.

Further, a through hole 34 is formed in the portion of the rear groupmovable body 30 corresponding to the output shaft 22 of the steppingmotor 20, and a rectangular concave portion 35 is formed around thethrough hole 34 in the front side of the rear group movable body 30.Further, a lead nut 36 is inserted and fixed inside the concave portion35. The lead nut 36 engages with the lead screw provided on the outputshaft 22 of the stepping motor 20, whereby the lead nut 36 and the reargroup movable body 30 move forward and backward following the positiveand reverse rotations of the output shaft 22.

Furthermore, the main guide pins 15 a are arranged to stand up even inthe corner portions of the low step portion 12 of the base 10, and thetip portion of the main guide pin 15 a attached to the top of the lowstep portion 12 is mounted so that movement is possible with respect tothe rear group movable body 30.

On the other hand, a front group movable body 40′ which supports thefront lens group is mounted to the tips of each of the guide pins 15 a,15 b provided on the high step portion 11. The front group movable body40′ is different from that of the first embodiment, and is set so as tobe capable of movement over a prescribed distance in the axialdirection. More specifically, the main guide pin 15 a is inserted in astate through the inside of a hole 44 formed to have an inner diameterroughly the same as the outer diameter of the main guide pin 15 a.

Further, circular stoppers 45 are attached to the tips of the sub guidepins 15 b. The outer diameter of the stoppers 45 is made one size largerthan the outer diameter of the sub guide pins 15 b. Further, the subguide pins 15 b described above are inserted in holes 46 formed inprescribed positions of the front group movable body 40′ to enablerelative movement. As for the inner diameter of the holes 46, the rearportion roughly matches the outer diameter of the sub guide pins 15 b,and the front portion is made one size larger than the outer diameter ofthe sub guide pins 15 b so that it is possible to at least insert andarrange the stoppers 45. Further, springs 47 are mounted in a coaxialstate at the tip side of the sub guide pins 15 b. Both ends of thesprings 47 make contact with the stoppers 45 and the inside surfaces ofthe holes 46 to bias the stoppers 45 and the inside surfaces apart.

In this way, because the positions of the stoppers 45 attached to thetips of the sub guide pins 15 b do not change with respect to the base10, the front group movable body 40′ is biased backward and fixed in thestate shown in FIG. 36 by the elastic restoring force of the springs 47.Further, as shown in FIG. 36, each dimension is set so that when therear group movable body 30 moves forward and is in a state makingcontact with the base 10, the front group movable body 40′ (front lensgroup) is positioned at the base position A, and the rear group movablebody 30 (rear lens group) is positioned at the base position (1).

Further, spacers 43 are inserted and arranged on the sub guide pins 15 bin a state fixed to the rear side of the front group movable body 40′.Of course, they do not necessarily need to be fixed to the front groupmovable body 40′, and may be in a free state, or may be fixed at therear group movable body 30 side. Further, the thickness of the spacers43 is set so that the distance between the front lens group and the rearlens group in the state where the front group movable body 40′ and therear group movable body 30 are both touching the spacers 43 matches thedistance d3 shown in FIG. 7, namely, the lens interval distance (C−(4))which obtains a zoom magnification of γ×.

Further, a through hole 41 is provided in the middle portion of thefront group movable body 40′, namely, at a position corresponding to thethrough holes 14, 32 provided in the base 10 and the rear group movablebody 30, and the front lens group is inserted and arranged inside thethrough hole 41.

By forming such structure, when the output shaft 22 of the steppingmotor 20 is rotated in reverse to move the rear group movable body 30backward to a base posture in contact with the front surface of the base10 as shown in FIG. 36(a), the zoom magnification can be set at 1×.

From this state, when the output shaft 22 of the stepping motor 20 isrotated in the positive direction to move the rear group movable body 30forward to a prescribed position (a position where there is no contactwith the front group movable body 40′, or even when there is contact itis not biased forward) as shown in FIG. 37, the zoom magnification canbe set at β× (e.g., 2×). Further, because the stepping motor 20 is usedas an actuator, by controlling the number of steps, it is possible tocontrol the position of the rear group movable body 30 with goodaccuracy.

In this state, the stepping motor 20 is rotated further in the positivedirection to move the rear movable body 30 further forward. When this isdone, as shown in FIG. 38, the rear group movable body 30 pushes againstthe front group movable body 40′ via the spacers 43, and this is pushedforward. In accordance with this, the front group movable body 40′ andthe rear group movable body 30 move forward together as one body.Further, the rotation of the stepping motor 20 is stopped at the timewhen the front group movable body 40′ is positioned at the frontposition C (the rear group movable body 30 is at the front-most position(4)). In this way, the zoom magnification can be set at Δ×. Accordingly,in the present embodiment, it is possible to obtain the three values1×→β×→γ×.

FIG. 39 shows a side view for explaining the concept in a fourteenthembodiment of the present invention. In each of the embodimentsdescribed above, optical zoom and focus were carried out, but in thepresent embodiment, macro is also carried out.

In the present embodiment, the lens drive apparatus is constructed sothat the front lens group 1 and the rear lens group 2 are arranged inthe front and rear of the optical axis L, the front lens group 1 isfixed at a fixed position, and the rear lens group 2 is moved in theoptical axis direction by drive means described later.

The front and rear lens groups 1, 2 are constructed in the same way sothat the lens groups are supported by being fitted inside annular frames3, 4, and each lens group has a lens diameter of about 5 mm. Further, aplurality of guide pins 7, 7 is arranged along the optical axis L, andthe front and rear frames 3, 4 which have holes provided in the outercircumference into which the guide pins 7, 7 are fitted are lined up inthe optical axis direction.

In order to function as a lens unit of an ultraminiature camera, animage taking element 6 such as a CCD or the like is arranged behind therear lens group 2. Accordingly, at the light-receiving position of theimage taking element 6, the magnification of the formed image changes inaccordance with the positional relationship of the three opticalelements lined up on the optical axis L, and the change in this zoommagnification generally has the characteristics shown in FIG. 40.

Namely, as for the general optical characteristics in the lens structureof the front and rear two groups, it is necessary to also move the frontlens group 1 to obtain the proper zoom magnification from wide-angle(WIDE) to telescopic (TELE), and in this regard, driving needs to becarried out in which the rear lens group 2 is moved in a linear state(characteristic b) toward the side of the body being photographed, andthe front lens group 1 is moved once toward the image taking element 6side and then returns to the side of the body being photographed in acurved state (characteristic f).

However, in this arrangement, because it is not possible to carry outminiaturization when it becomes necessary to provide separate drivemeans to move the front lens group 1, in the present embodiment, thefront lens group 1 is fixed (characteristic c) at a fixed position, andonly the rear lens group 2 is moved in the optical axis direction,wherein the rear lens group 2 is stopped at the two fixed positions A,B. In this way, the zoom magnification can be set at A× at the fixedposition A, and the zoom magnification can be set at B× at the fixedposition B, and this makes it possible to achieve a lens drive apparatushaving two values of zoom magnification.

To give a specific example, in the case where the distance between theimage taking element 6 and the front lens group 1 is fixed at 11.259 mm,the zoom magnification becomes 1× at the time when the distance from theimage taking element 6 to the rear lens group 2 is 2.367 mm, and thezoom magnification becomes 2× at the time when such distance is 4.184mm.

Further, in the present invention, driving is carried out so that therear lens group 2 is moved a minute distance for each of the stoppedfixed positions A, B. The minute movement at each of these fixedpositions A, B is set so that movement is carried out at feed pitchintervals of 50 μm or less for a section of at least 600 μm forward andbackward. These numerical values are different than the ideal values inaccordance with the design values of the optical system, but they areconfirmed by experiment. Specifically, as shown in FIG. 41, at the fixedposition A at the side near the image taking element 6, a macro focalpoint having an objective distance of 5 cm is obtained by carrying outmovement of about 300 μm toward the side of the body being photographed.At this time, the image forming magnification is changed to aboutA+0.1×, but the macro operation is carried out by driving which moves aminute distance at such fixed position A. Further, at the fixed positionB at the side near the front lens group 1, a macro focal point having anobjective distance of 5 cm is obtained by carrying out movement of aboutseveral 100 μm toward the image taking element 6 side. At this time, theimage forming magnification is changed to about B−0.1×, but the macrooperation is carried out by driving which moves a minute distance atsuch fixed position B.

Further, as confirmed by experiment, when the distance of minutemovement at each of the fixed positions A, B is several 10 μm, thismatches the position where the focal point is 30 cm, and when thedistance is 10 μm, this matches the position where the focal point is 1m.

Further, with regard to the driving of the rear lens group 2, the feedpitch of the minute movements is also set at several μm or less. In thisway, by making the feed pitch smaller, it is possible to carry outfocusing at such fixed positions, whereby the focus operation becomeseasy.

Accordingly, even in a structure in which only the rear lens group 2 isdriven by one actuator, a zoom operation having two values and aprescribed distance macro operation are carried out, and the focusoperation is also easily carried out. Further, it is possible to use astepping motor as an actuator to move the rear lens group 2 back andforth between the two fixed positions A, B.

A more specific structure for achieving the operation principledescribed above can be achieved by using the structure of the firstembodiment shown in FIG. 8 and FIG. 9, and appropriately adjusting thecontrol of the stepping motor used as a driving source. In this regard,the present embodiment will be described with appropriate use of FIG. 8and FIG. 9. First, FIG. 8 is a perspective drawing showing each portionseparately, FIG. 9(a) shows the state where the zoom magnification is A×(base posture), and FIG. 9(b) is a perspective drawing showing the statewhere the zoom magnification is B×. Further, because the mechanicalstructure is the same as the first embodiment, a description of the sameportions is omitted.

In the present embodiment, spacers 43 are inserted and arranged on eachguide pin 15. The thickness of the spacers 43 is adjusted. In thedriving of the stepping motor 20, the movement position of the reargroup movable body 30 can be positioned with good accuracy in accordancewith the number of steps, the rear group movable body 30 is movedbackward by rotating the output shaft 22 in the reverse direction andstopped at the fixed position A near the front surface of the base 10 asshown in FIG. 9(a), and with this forming the base posture, the zoommagnification is set at A×. From this state, by rotating the outputshaft 22 in the positive direction, the rear group movable body 30 ismoved forward and stopped at the fixed position B near the spacers 43 asshown in FIG. 9(b), and here the zoom magnification is set at B×.

Further, driving is carried out to move minute distances for each of thefixed positions A, B. In this regard, the stepping motor 20 is atwo-phase type with 12 steps, for example, and by using a lead screwhaving a 0.5 mm pitch, it is possible to achieve a feed of approximately42 μm per one step in two-phase magnetization, and the switching tomacro operation is carried out by feeding several steps.

In the focus operation, the feed pitch needs to be made smaller, andwhen the stepping motor has 20 steps and uses a 0.25 μm pitch, forexample, a feed of 12.5 μm is carried out per one step. Further, if 1-2phase driving is carried out, because a feed of 6.25 μm is carried outper one step, the focus operation is carried out more accurately.

In this way, by driving the stepping motor 20, it is possible to movethe rear group movable body 30, namely, the rear lens group to the fixedpositions A, B, and minute movement is carried out at each of the fixedpositions A, B. Accordingly, a zoom operation having two values and aprescribed distance macro operation are carried out by one actuator, andby making the feed pitch of the minute movements several μm or less, itis possible to carry out focusing at such fixed positions, and the focusoperation is also easily carried out.

Further, in the lens drive apparatus having the structure describedabove, in one example of the dimensional shape, the base 10 is 11 mmsquare, the inner diameter of the through holes 32, 41, namely, thediameter of the rear lens group and the front lens group is 5 mm, andthe height of the entire apparatus (the distance from the bottom surfaceof the base 10 to the front surface of the front group support body 40)is approximately 11 mm. In this way, it can be adequately installed in aportable telephone.

Further, when considering the dimensional shape of existing portabletelephones, the surface area of the camera module forms a size less than13 mm square even for fixed focusing. When this level is used as anupper limit, the lens drive apparatus can be made one size larger with alens diameter up to about 7 mm, and this makes it possible to keep thetotal size (flat shape of the base 10) under 13 mm square. Of course,the use of a smaller lens does not interfere with the design of furtheroverall miniaturization.

INDUSTRIAL APPLICATION

As described above, in the lens drive apparatus according to the presentinvention, by limiting the stopping positions of the lens supportmembers to a small number such as 1, 2 or 3 (limiting the zoommagnification), it is possible to carry out positioning by a simplemechanism without the need for a complex cam mechanism or highlyaccurate control or complex mechanisms, and this makes it possible toconstruct a simple miniature lens drive apparatus at low cost. For thisreason, it becomes possible to install such apparatus as a lens driveapparatus corresponding to optical zoom in portable telephones and thelike.

Further, in the lens drive apparatus according to the present invention,the front lens is fixed, and only the rear lens connected to drive meansis moved and stopped at two fixed positions, and because there ismovement over a minute distance at such fixed positions, a zoomoperation having two values and a prescribed distance macro operationare carried out. Further, by making the feed pitch of the minutemovements less than or equal to several μm, it is possible to carry outfocusing at such fixed positions, and the focus operation is also easilycarried out. As a result, the external shape can be ultraminiaturized,and this makes it possible to install the apparatus preferably inportable telephones which are becoming thinner and smaller scale.

Having described and illustrated the principles of the invention invarious embodiments thereof, it should be apparent that the inventioncan be modified in arrangement and detail without departing from suchprinciples. We claim all modifications and variations coming within thespirit and scope of the following claims.

1. A lens drive apparatus for moving lenses in a lens unit having anoptical zoom function for use in an ultraminiature camera which useslenses having an optically effective lens diameter of 7 mm or less,comprising: first and second lens support members arranged in the frontand back; wherein each of said first and second lens members holds aprescribed number of lenses; said first lens support member is fixed;said second lens support member is made movable in the forward andbackward directions, and is constructed so as to stop at two prescribedpositions in the forward and backward directions; whereby it is possibleto switch between two kinds of zoom magnification.
 2. A lens driveapparatus for moving lenses in a lens unit having an optical zoomfunction for use in an ultraminiature camera which uses lenses having anoptically effective lens diameter of 7 mm or less, comprising: first andsecond lens support members arranged in the front and back; wherein eachof said first and second lens members holds a prescribed number oflenses; said first lens support member is made movable in the forwardand backward directions, and is constructed so as to stop at twoprescribed positions in the forward and backward directions; said secondlens support member is made movable in the forward and backwarddirections, and is constructed so as to stop at two prescribed positionsin the forward and backward directions; whereby it is possible to switchbetween two kinds of zoom magnification by controlling the stoppingpositions of said first and second lens support members.
 3. A lens driveapparatus for moving lenses in a lens unit having an optical zoomfunction for use in an ultraminiature camera which uses lenses having anoptically effective lens diameter of 7 mm or less, comprising: first andsecond lens support members arranged in the front and back; wherein eachof said first and second lens members holds a prescribed number oflenses; said first lens support member is made movable in the forwardand backward directions, and is constructed so as to stop at twoprescribed positions in the forward and backward directions; said secondlens support member is made movable in the forward and backwarddirections, and is constructed so as to stop at three prescribedpositions in the forward and backward directions; whereby it is possibleto switch between three kinds of zoom magnification by controlling thestopping positions of said first and second lens support members.
 4. Thelens drive apparatus described in any one of claim 1˜claim 3, whereinthe movement of at least one of said first lens support member and saidsecond lens support member is carried out based on the output of astepping motor.
 5. The lens drive apparatus described in claim 1 orclaim 2, wherein at least one solenoid, relay or permanent magnet isused as an actuator to move said first lens support member and saidsecond lens support member, whereby the switching of the two kinds ofrelative positional relationship can be controlled by moving the firstand second lens support members in accordance with the output of theactuator.
 6. The lens drive apparatus described in claim 3, wherein saidsecond lens support member receives the output of a stepping motor tomove forward and backward, and said first lens support member is mademovable by a biasing force from said second lens support member and isstopped at the two positions of a first position in the state when saidbiasing force is not received, and a second position when being moved bysaid biasing force.
 7. A lens drive apparatus for moving lenses in alens unit having an optical zoom function for use in an ultraminiaturecamera which uses lenses having an optically effective lens diameter of7 mm or less, comprising: first and second lens support members arrangedin the front and back; wherein each of said first and second lensmembers holds a prescribed number of lenses; said first lens supportmember is fixed; said second lens support member is made movable in theforward and backward directions, is constructed so as to stop at twofixed positions in the forward and backward directions, and is driven tomove a minute distance at said fixed positions; whereby it is possibleto carry out operations which change optical zoom and focus.
 8. The lensdrive apparatus described in claim 7, wherein the minute movement atsaid fixed positions carries out movement by a feed pitch less than orequal to 50 μm for at least a 600 μm section front and back.
 9. The lensdrive apparatus described in claim 8, wherein the feed pitch of saidminute movement is made less than or equal to several μm.
 10. The lensdrive apparatus described in any one of claim 7 claim 9, wherein astepping motor is used as a drive source in drive means for moving saidsecond lens support member, a lead screw is provided on the output shaftof the stepping motor, a lead nut is provided at a correspondingposition of said second lens support member, and a linear operation iscarried out by connecting the lead screw and the lead nut.
 11. The lensdrive apparatus described in claim 10, wherein said stepping motor is aflat type in which steps are arranged on the left and right of therotor.